The ovens used for baking food products based on a cereal paste vary depending on the specific type of product to be baked. At present there does not exist any standard oven suitable for baking all the types of product in satisfactory manner.
Thus, for crackers, and for soft items such as sponge, it is general practice to use direct gas flame (DGF) ovens.
For pastes from rotary machines or pastes that are extruded and cut to length, cyclothermal or forced-convection ovens are used, in addition to DGF ovens.
Nevertheless, best baking results can be obtained only by using DGF ovens for crackers and soft items, and cyclothermal or forced-convection ovens for-rotary-machine or cut pastes, with the precise configuration of each oven being adjusted in practically unalterable manner for each type of paste.
As presently designed, DGF ovens suffer from drawbacks such as:                possible pollution of food by combustion products;        difficulties in regulating baking; and finally        problems of burner maintenance. For example, with Venturi type burners, it is possible for heat flux to get back to the burner, which can damage it, if poorly dimensioned.        
With forced convection in present ovens, the energy conveyed by the flow of hot air is dissipated essentially in the form of a convective flux.
At a higher temperature, the energy could be dissipated, in addition or mainly, as radiant flux. This depends on temperature, on flow rate, and on flow speed.
With forced convection, there does not exist any oven in which the temperature of the baking chamber can reach temperatures in the range 350° C. to 400° C. with air at a speed that is less than or equal to 0.5 meters per second (m/s). Unfortunately, that is what is required to obtain a significant radiant flux for baking certain “soda” crackers. Furthermore, the speeds needed in present ovens lie in the range 3 m/s to 6 m/s (at the outlet from the nozzle). Unfortunately, such speeds do not enable light items to be baked since they are blown away by the flow of air inside the oven.
There also exist “impingement” ovens which are forced-convection ovens with air speeds not less than 20 m/s.
Nor do there exist any combined DGF and forced-convection ovens in which it is possible within a single module to modulate, in controlled manner, the quantities of energy supplied by each of those two modes.